On 25 May 2015, Komorowski conceded the presidency of Poland to the rival candidate Andrzej Duda, after the latter gained a 51.5% majority in the second round of the presidential election, the closest election in Polish history.

Bronisław Maria Komorowski was born in Oborniki Śląskie. He is a member of Komorowski noble family. Born as a son of Zygmunt Leon Komorowski (1925–1992), professor of African Studies at the University of Warsaw and Jadwiga Komorowska (née Szalkowska) (1921–).[2]

From 1957 to 1959 he lived in Józefów near Otwock. From 1959 to 1966 he also attended elementary school in Pruszków. In 1966 he transferred to Warsaw and graduated from Cyprian Kamil Norwid High School no. 24. For many years he was affiliated with the Scout Movement.[3] During his studies he was a Scout instructor in 208 WDHiZ "Parasol" Battalion in Mokotów. He met his future wife through Scouting.[4]

In 1977 he finished his studies in history at the University of Warsaw. From 1977 to 1980 he was an editor at the journal Słowo Powszechne.

As a candidate of the Democratic Union he was elected to parliament in 1991 and in 1993. In 1997, during the 2nd Sejm, together with a group of Warsaw University activists under the management of Jan Rokita he created Koło Konserwatywno-Ludowe. In the same year Koło Konserwatywno-Ludowe joined the newly created Conservative People's Party (SKL), which joined Solidarity Electoral Action (AWS). In September 1997 Komorowski was elected as a candidate of AWS. From 1997 to 2000 he presided over the Parliamentary National Defence Committee, and from 2000 to 2001 served as the minister of national defence in the government of Jerzy Buzek. In 2001, while still a minister in the minority AWS government, Komorowski, along with some activists from SKL, became a member of Civic Platform (PO). He stood for election to the 4th Sejm as a candidate of PO. Again he was elected, this time for the Warsaw constituency. After the inauguration of the new parliament he resigned from SKL. Since 2001 he has been a member of the National Civic Platform Board. In the 4th Sejm he was the deputy chairman of the Parliamentary National Defence Committee and a member of the Parliamentary Committee on Foreign Affairs.

He won election to the 5th Sejm in a district outside Warsaw. On 26 October 2005, he was elected Vice Speaker of the Sejm. 398 MPs voted in favour of his candidacy. His party had earlier recommended him as a candidate for Speaker. His candidacy, in defiance of precedent, was rejected by Law and Justice (PiS) which voted for Marek Jurek. This created an unfavourable climate further discussions regarding a PO-PiS coalition.

After the resignation of Marek Jurek as Speaker of the Sejm on 25 April 2007 Civic Platform announced Komorowski's candidacy for Speaker. On 27 April 2007 the Sejm rejected his nomination, and Ludwik Dorn from PiS became a new marshal. 189 MPs voted for Komorowski. Komorowski became Vice Speaker.

Komorowski became acting president on 10 April 2010 following the death of President Lech Kaczyński. His first decision was to announce seven days of national mourning beginning on 10 April.[7] According to the Constitution of Poland, Komorowski was required to set a date for the next presidential election within 14 days of assuming the position, the election date coming within 60 days of that announcement. On 21 April, his office announced that the election would be held on 20 June.[8] In the election, he got 41.54% of votes in the first round and then faced Jarosław Kaczyński, who got 36.46% of votes in the first round.

In the runoff Komorowski was elected president (8 933 887 valid votes, 53,01%) and formally took office on 6 August 2010.

Following his election, Komorowski announced that he would resign from the Sejm on 8 July 2010, and thus cease to be a marshal and an acting president (his successor as an acting president was the next marshal of the Sejm Grzegorz Schetyna, who held the position for about a month before Komorowski's formal inauguration).[13] Komorowski currently resides and works in the Belweder Palace instead of the Presidential Palace.

On 25 May 2015, following his defeat in the second round of the 2015 presidential election, Komorowski conceded the presidency to rival Andrzej Duda, after the latter won a 51.5% majority. This was the tightest election of Polish history. His term ended on 6 August 2015, when Duda was sworn in as a new president.

Komorowski has been married to Anna Dembowska since 1977. The couple has five children: Zofia Aleksandra (born 1979), Tadeusz Jan (born 1981), Maria Anna (born 1983), Piotr Zygmunt (born 1986) and Elżbieta Jadwiga (born 1989).